This invention relates to an automatic transmission system for vehicles which is capable of easily selecting a suitable gear change map out of a plurality of gear change maps.
There have been proposed various automatic transmission systems for vehicles which are adapted to detect the amount of depression of an accelerator pedal and the speed of the vehicle and compute an optimum gear position for each instant based on a predetermined gear change map, thereby to control the gear position of a gear-type transmission according to the result of the computation. In the automatic transmission systems of this type, as the optimum gear position is determined by the amount of depression of the accelerator pedal and the speed of the vehicle, if, for example, the accelerator pedal is released on an upward slope to negotiate a curve or the like, the transmission will be shifted up and if the accelerator pedal is again depressed after the curve, the transmission will be shifted down. This is sensed as poor vehicle response by the driver.
In order to eliminate this disadvantage, there has been proposed another type of automatic transmission system for vehicles which is provided with, for example, a first-gear position and/or a second-gear position in addition to a drive-gear position (D-position) and which automatically carries out gear-change operations over all of the gears according to the amount of depression of the accelerator pedal and the speed of the vehicle so that the transmission may be held in the first-gear position or may effect gear-change within the first-gear position and the second-gear position.
However, in the automatic transmission system having multi-gear positions, if a gear-holding position is provided for every gear, the number of shifting positions of the selector will be increased and the operational ease which is a key feature of the ordinary linear-type selector will be spoiled. On the other hand, if an H-type shifting lever of the type employed with conventional manual transmissions is used instead of the linear type selector, the switch mechanism for detecting the position of the shifting lever will be made complicated and the safety device for preventing the shifting lever from being erroneously moved from the D-range position to the reverse-gear position (R-position) will also be made complicated.
Further, Japanese Patent Publication Disclosure No. 59-97351 discloses, an automatic transmission system wherein a basic gear change map can be synthesized with additional gear change maps selectable according to the driver's taste or the use of the vehicle so as to obtain a desired gear change map.
Although this automatic transmission system enables gear changing to be effected according to an optimum gear change map suited to the driver's taste or the use of the vehicle, it is disadvantageous in that it requires a mode selecting switch, a memory switch, etc. in addition to the selector lever. This makes the operation complicated and increases the driver's work.